Antibiotics Linked with Increased Arrhythmias and Death Risk

A new study indicates that short-term treatment with the antibiotics azithromycin and levofloxacin may increase the risk of serious cardiac arrhythmias and death.

Research has shown a relationship between azithromycin use and an increased risk of cardiovascular death and all-cause mortality in Medicaid patients, especially those at a high risk for cardiovascular disease, Pharmacy Times reports. These findings led the Food and Drug Administration (FDA) to issue a public safety warning in March 2013 about potential risks associated with azithromycin and similar risks linked with levofloxacin. Azithromycin is sold under the brand names Zithromax, Zmax, and AzaSite; levofloxacin under the brand names Levaquin, Quixin, and Iquix.

The new study, published in the March/April 2014 issue of the Annals of Family Medicine, analyzed data from military veterans treated with azithromycin, levofloxacin, or amoxicillin. The researchers examined data for 14 million patients treated at 140 veterans medical centers and 600 outpatient clinics from September 1999 through April 2012. They evaluated the risks of cardiac arrhythmia and death associated with each antibiotic. Azithromycin treatment typically lasted five days; amoxicillin and levofloxacin treatment was usually for 10 days.

Azithromycin and levofloxacin were associated with a significant increase in the risk of death and serious arrhythmia, Pharmacy Times reports. A weighted analysis showed 228 patients treated with azithromycin and 384 treated with levofloxacin per million antibiotics dispensed died after five days of treatment, compared with just 154 deaths in patients treated with amoxicillin. Ten days after the start of treatment, 422 azithromycin patients and 714 levofloxacin patients died per million antibiotics dispensed, compared with 324 amoxicillin patients.

In the first five days of treatment, patients on azithromycin had a 48 percent increased risk of death and a 77 percent increased risk of serious arrhythmia compared with amoxicillin patients. Six to 10 days in, however, the risks were not significantly increased compared with amoxicillin. Levofloxacin users had a 149 percent increased risk of death and a 143 percent increased risk of serious arrhythmia in the first five days compared with those who took amoxicillin and the increased risks remained significant throughout the 10-day treatment period. The risk of death increased 95 percent and the risk of serious arrhythmia increased 75 percent, according to Pharmacy Times.

The authors say their findings support safety announcements and they suggest doctors should consider the risks and benefits of the antibiotics before making prescribing decisions, according to Pharmacy Times.